Entity

Time filter

Source Type


Voicescu M.,Institute of Physical Chemistry Ilie Murgulescu | Ionescu S.,University of Bucharest | Gatea F.,Romanian National Institute for Research and Development for Biological Sciences
Journal of Fluorescence | Year: 2014

Photophysical properties of five hydroxyflavones (HF) (some typical models of flavonols), (3 - HF, 6 - HF, 7-HF, 3, 6 - diHF and 3, 7 - diHF) were studied in homogeneous media by means of UV-vis and steady-state and time resolved fluorescence spectroscopies. Their absorption and fluorescence characteristics based on the flavonols structure are presented and discussed. It was found that the fluorescence of the flavonols depends on the nature of the solvent and on their molecular structure, especially on the position and the number of the -OH groups of the substituted phenyl ring. Attention is paid to the number of the -OH groups that influence the excited-state intramolecular proton transfer (ESIPT) process. The fluorescence quantum yield and the lifetime of the flavonols in heterogeneous media have been also determined. The results are discussed with relevance to the flavonols as sensitive fluorescence probe and to their microenvironments in the systems of biological interest and especially in a typical protein environment. © 2013 Springer Science+Business Media New York. Source


Gaspar A.,Romanian National Institute for Research and Development for Biological Sciences
Journal of medicine and life | Year: 2011

The aim of this study was to obtain four collagen based porous scaffolds and to assess their in vitro biocompatibility and biodegradability in order to use them for skin tissue engineering. We have prepared four variants of collagen-based biodegradable sponges by liophilization of type I collagen solution and three variants of collagen-agarose mixture in different ratios 2:1 (A), 1:1 (B) and 1:2 (C). These scaffolds had microporous structure with a higher than 98% porosity and a reduced biodegradation after their exposure to UV radiation. The incorporation of agarose into the collagen scaffolds has improved their structural stability. In vitro biocompatibility testing for the four types of sponges was performed on a stabilized fibroblast cell line and showed that both cell viability and morphology were not altered by collagen and collagen-agarose variants A and B sponges. These three porous sponges demonstrated potential for future application as cell scaffolds in skin tissue engineering. Source


Litescu S.C.,Romanian National Institute for Research and Development for Biological Sciences
Advances in Experimental Medicine and Biology | Year: 2010

A comprehensive description of the most frequently used methods to determine the antioxidant activity in food and raw materials is given. The methods are classified into two categories, depending on the type of the assessment carried out. Several methods for the assessment of antioxidant efficacy using free radical scavenging such as Oxygen Radical Absorbance Capacity Assay (ORAC), Total Radical Trapping Antioxidant Parameter assay (TEAC), Ferric reducing antioxidant power assay (FRAP) and 2,2′-diphenyl- 1-picrylhydrazyl (DPPH) assay are described. An example of methods based on the assessment of antioxidant efficacy using significant biological substrates is also presented. Critical opinions concerning the proposed methods are presented. © 2010 Landes Bioscience and Springer Science+Business Media, LLC. Source


Litescu S.C.,Romanian National Institute for Research and Development for Biological Sciences
Advances in Experimental Medicine and Biology | Year: 2010

Antioxidants are groups of chemical substances, the most abundant being polyphenols, mainly found in plants, fruits and vegetables. They include flavonoids, flavonoid derivatives, polyphenols, carotenoids and anthocyanins. Currently, the nutritional quality of many foodstuffs is guaranteed by the presence of antioxidant compounds. The importance of these chemicals as indicators and preservatives of nutritional quality makes necessary the development of accurate, versatile and rapid analytical tools necessary to detect their presence in many foodstuffs and to assess their antioxidant efficacy. In this chapter, enzyme-based biosensors such as monophenol monooxygenase (tyrosinase), catechol oxidase (laccase) and horseradish peroxidase (HRP) are reviewed. Actually, these biosensors are the most commonly used for the detection of polyphenols and flavonoids content. © 2010 Landes Bioscience and Springer Science+Business Media, LLC. Source


Calugar A.,Romanian National Institute for Research and Development for Biological Sciences
Acarologia | Year: 2013

The present study analyzes the effects of pollution with cement powder on the Gamasina mite communities from soil organic horizon of some forest ecosystems. The study was carried out in two main polluted areas - one situated in Southern Romania (Cement Plant from Câmpulung Muscel - Arges County) and the other one in the North-East (the Tasca-Bicaz Cement Plant - Neamt County). Forest ecosystems located at different distances from the pollution sources were studied and the seasonal dynamics of both the gamasid fauna and community structures were monitored. The study focused on the suborder Gamasina Leach 1815, but the total abundance of the uropodids (Uropodina Kramer, 1882) was also considered. It was found that the percentage of Gamasina mites among all mites was higher in the control forests than in the polluted ecosystems, which was true for both polluted areas. Considering their ecological requirements, their habitat preference, vertical distribution in the soil, and seasonal population changes were investigated. In polluted biotopes, the Gamasina communities suffered from lower densities, fewer species and replacement of some species with others. The analysis of the Gamasina species distribution in the control and polluted ecosystems suggests that some species can be considered tolerant, such as certain representatives of Zerconidae, Parasitidae, Pachylaelapidae, Veigaiidae etc. © Cǎlugǎr A. Source

Discover hidden collaborations